Controlled nitrate feeding strategies for fed-batch cultures of microalgae were applied for the enhancement of lipid production and microalgal growth rates. In particular, in this study, the effect of nitrate feeding rates on lipid and biomass productivities in fed-batch cultures of Nannochloropsis gaditana were investigated using three feeding modes (i.e., pulse, continuous, and staged) and under two light variations on both lipid productivity and fatty acid compositions. Higher nitrate levels negatively affected lipid production in the study. Increasing the light intensity increased the lipid contents of the microalgae in all three fed-batch feeding modes. A maximum of 58.3% lipid- to dry weight ratio was achieved when using pulse-fed cultures at an illumination of 200 μmol photons m⁻² s⁻¹ and 10 mg/day of nitrate feeding. This condition also resulted in the maximum lipid productivity of 44.6 mg L⁻¹ day⁻¹. The fatty acid compositions of the lipids consisted predominantly of long-chain fatty acids (C:16 and C:18) and accounted for 70% of the overall fatty acid methyl esters. Pulse feeding mode was found to significantly enhance the biomass and lipid production. The other two feeding modes (continuous and staged) were not ideal for lipid and biomass production. This study demonstrates the applicability of pulse feeding strategies in fed-batch cultures as an appropriate cultivation strategy that can increase both lipid accumulation and biomass production.

中文翻译：

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硝酸盐饲喂策略对小拟球藻分批补料培养中脂质和生物量生产力的影响

微藻分批补料培养的受控硝酸盐补料策略用于提高脂质产量和微藻生长速率。特别是，在本研究中，使用三种进料模式（即脉冲、连续和分阶段）和在两种脂质的两种光照变化下，研究了硝酸盐进料速率对加迪纳微拟球藻分批补料培养物中脂质和生物量生产率的影响。生产力和脂肪酸组成。较高的硝酸盐水平对研究中的脂质产生产生负面影响。在所有三种补料分批喂养模式中，增加光强度会增加微藻的脂质含量。^{当在 200 μmol 光子 m -2}的光照下使用脉冲补料培养物时，脂质与干重的比率最大达到 58.3% s ^-1和 10 mg/天的硝酸盐喂养。该条件还导致最大脂质生产力为 44.6 mg L ^-1 天^-1。脂质的脂肪酸组成主要由长链脂肪酸（C:16 和 C:18）组成，占总脂肪酸甲酯的 70%。发现脉冲饲喂模式显着提高了生物量和脂质的产生。其他两种喂养模式（连续和分阶段）对于脂质和生物质生产并不理想。这项研究证明了脉冲饲喂策略在补料分批培养中的适用性，作为一种可以增加脂质积累和生物量生产的适当培养策略。